"The crew attempted to make an aggressive rapid attack but they weren't able to make entry," Clarke said.

At one point there were 19 trucks and about 50 firefighters on the scene, Clarke added.

Firefighters remained at the scene late into Sunday evening, dealing with remaining hot spots.

Officials say the fire started at a unit in the centre of a block of units but, because of the structure of the complex, the fire spread rapidly in both directions.

After the fire was out, Peel Regional Police Const. Lillian Fitzpatrick said it was the responding firefighters who confirmed the tragic news that a boy had died.

"When firefighters went through, they located the body of the child inside a unit," Fitzpatrick told reporters on Sunday morning, just a few hours after the fire had started.

The boy, whom friends of the boy's mother have identified as Nicolas Gabriel, was sleeping over at a friend’s house.

Brampton Mayor Susan Fennell had spoken to the family after they received the news of his death on Sunday.

A displaced resident sits near the townhouse complex. The huge fire has destroyed or damanged 18 units and left between 80 to 100 people homeless, according to Peel Regional Police. (Michael Cole/CBC)

"Right now, they’re in shock," she said. "I mean it's so profound — your son is on a sleepover and somebody comes and knocks on your door and says your son is missing and then they confirm that your son has passed away in the fire. They’re in shock, they’re in disbelief."

"To have a second tragedy of a loss of a young life is a nightmare," she said.

'Nothing but the clothes on their backs'

The blaze on Ardglen Drive left 18 units severely damaged or destroyed, according to police. They say between 80 and 100 people have been left homeless.

"These people had to leave in the very early morning hours with nothing but the clothes on their backs," Fitzpatrick said.

That meant that a number of people fled for safety wearing just pyjamas or robes.

Fitzpatrick said between 200 and 300 people were evacuated from the area, though that figure included those who lived in adjacent units, along with those living in the units that burned.

Tressa Daley and her husband fled their home as fast as they could, after waking up to discover the fire that had broken out in the middle of the night. (CBC)

Tressa Daley was among the residents whose homes were destroyed. She told CBC News that she and her husband lost everything in the fire.

Daley said her husband jumped out of bed in the middle of the night. He looked out the window and told her they had to get out.

"He turned the lights on and he could see the glare from the flames coming off of the back of the building," Daley told CBC News in an interview on Sunday.

Daley said the couple quickly threw on clothes and got moving.

'Orange flames and lots of black smoke'

"When we went to go through the front door, the smoke was already starting to come through the front door. And we went out the back and came outside to see orange flames and lots of black smoke," she said.

The smoke was thick and black. It was making it hard to breathe, Daley said.

Fitzpatrick said the fire has had a profound effect due to the sheer number of people involved.

"Their homes are gone and they were forced to evacuate those homes without taking anything with them," she said. "So [for] the people that are involved and for their families, this has been a devastating, devastating fire."

Fitzpatrick said that residents have been supporting one another since they first learned of the fire. Some knocked door to door to get their neighbours out.

Peel Regional Police Const. Lillian Fitzpatrick said that the people living in the Ardglen Drive townhouse complex were forced to flee their homes, in the middle of the night, with 'nothing but the clothes on their backs.' (CBC)

"They have that common bond that … they know exactly where they stand at this point and it's bringing them together," she said.

The fire is being investigated by the coroner, by police and by the Ontario Fire Marshal's office.

Food and clothing donations have been pouring in to help out those left without a home on Sunday night.

Alain Normand, the emergency manager for the City of Brampton, said it was great to see that the community could pull together in a time of need.

But the city said the most critical need is for cash donations.

Most of the people who have been displaced are believed to be staying with family on Sunday evening. But some will close out the weekend sleeping in a shelter.

Authorities will be working with each family to relocate them for the short and long-term.

"Some have insurance, some don't. Some lost everything, some didn't. So we have to do a systematic valuation, family by family … so we can provide them with the help that is really required," Normand said.

With reports from the CBC's Ivy Cuervo, Tashauna Reid and The Canadian Press